Dynamo-electric machine



(No Model.)

T. AEDISON. DYNAMO BLEOTRIG MACHINE.

No. 298,954. Patented. May 20, 1884.,

N. PETERs. Phnlo-Lnhogriplmr. wuhin tmn. c.

NITED STATES PATENT ()Frica THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY.

DYNAMO-ELECTRIC MACHINE.

eencrrrcarron forming part of Letters Patent inc/298,954, dated May 20,1884. Application filed December 12, 1883. (No model.)

To all whom it may concern:

Be it known that I, THOMAS A. EDIsoN, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented a new and usefulImprovement in Dynamo-Electric Machines, (Case No. 600,) of which thefollowing is a specification.

In my Patent No. 276,233, dated April 24, 1883, are set forth theadvantages of the use of current-collectors forming bridges of 'highresistance between the bars of the commutator-cylinder of adynamo-electric machine or electro-dynamic motor, whereby the spark atthe commutator-bars, due to the breaking of local circuits, is preventedand in said patent is described the use for this purpose ofcurrent-collectors of inferior conducting capacity, making inferiorcontact at the surface of the commutator-cylinder.

My present invention relates to a different means of forming suchhigh-resistance connections between'the commutator-bars. Instead ofmaking inferior contact at the commutatoncylinder, or forming thecurrent-collector of inferior conducting material, I place the desiredhigh resistance external to the current-collector, between it and thepoint of connection with the main conductor leading from the machine. Ido this by using a divided commutator-brush composed of alternate layersof metal, preferably copper, and insulating material, and connecting allthe metallic layers together through external con ductors having thedesired high resistance. The local current then, which passes throughthe brush from one commutator-bar to another, encounters the resistanceof these separate conductors, having to pass through them to and fromtheir point of connection together; and, therefore, as explained in thepatent above referred to, this local current will be weak and thebreaking at the surface of the cylinder of the local circuit willproduce little or no spark.

My invention is illustrated in the annexed drawings, in which Figure 1is a View in elevation of a portion of a dynamo-electric ma chineembodying said invention; Fig. 2, a' view of one of the strips of thecommutatorbrush with the resistance-conductor attached thereto; Fig. 3,a side view ofthe brush and resistance-conductor with the clampingsleevein section, and Fig. 4 a cross-section of the brush.

A A are the field-magnet poles of a dynamoelectric machine orelectro-dynamic motor. B is the armaturethereof, andO the bed-plate, thelower portion of which is broken away in the drawings.

The commutator-brushes a a areeach formed of several strips, b, ofcopper or other suitable metal, whose bearing ends are preferablydivided by several slots or notches, c c, to divide and diminish sparkat the ends.

To each metal strip 1) is attached a thin strip of metal, (Z. This maybe copper, in which case it would be made of the desired resistance byproperly proportionin g its length and sectional area; or a strip ofGerman silver or other high-resistance metal may be used, which would ofcourse be larger and shorter than a copper strip. strips are solderedtogether at d.

The ends of all these 4 Between the metal strips of the brush are placedlayers 0 of insulating material. Mica or asbestus is a suitable materialfor this purpose. The insulating-layers extend back close to the ends ofthe resistancestrips, and such ends are soldered together, and are allconnected to the main conductor- Around the brush, at the outer end ofthe bearing-strips, is placed a sleeve of insulating material, whichholds the metal and insulating-strips together, a wedge, f, of wood orother suitable material, being inserted within-the sleeve to secure theWhole tightly.

Instead of a single bearing-strip, b, with its end divided intofingers,several separate strips or wires may be secured to theresistance-strip cl. The insulating-strips 0, preferably, but

not necessarily, are similarly divided. The ends of all the metal stripsbear upon the commutatorcylinder, and the local circuit formed when thebrush bridges the commutator-bars is around the outer end of theresistance-strips.

Any suitable number of currentcollectors to produce the totalconductivity required may be used on each side of thecommutatorcylinder.

The circuit-connections fromthe ends of the resistancestrips arepreferably made in the manner shown, conductors 9 extending throughinsulating-tubes h to clampingplates on the bed-plate of the machine.

It is evident that many details-such as the form and arrangement of theexternal resistanees1nay be modified without departing from the spiritof my invention.

\Vhat I claim is- ,1. An eleetrically-divided current-collector each ofwhose divisions is of such width as notto bridge the space between thecommutator-bars, in combination with a resistance external to saidbruslni'orming a high-resistance bridge between said bars, substantiallyas set forth.

2. The eurrent-eollector formed of alternate layers of metal andinsulation, in combination with resistances external to saidcurrent-collcctor through which the metal layers are con neeted,substantially as set forth.

3. The combination of the metal-bearing strips or wires of aeurrent'colleetor, resistances attached thereto and connected togetherand to the main conductor, and insulating ma terial between the bearingends and between the resistances, substantially as set forth.

4. The combination, with the metal bearing-strips and the interposedinsulation, of the insulating-sleeve holding them together,substantially as set forth.

5. The combination, with the metal bearing; strips and the interposedinsulation, of the insulating-sleeve and wedge holding them together,substantially as set forth.

(3. The eiu-rent-oolleetor formed of strips or metal and interposedinsulation, in combination with resistance-strips attached at one end tosaid metal strips, and all connected together at their other ends,substantially as set forth.

This specification signed and witnessed this 15th day of November, 1883.

THOS. A. EDISON. \Vitnesses:

H. \V. SEELY, EDWARD II. Pya'r'r.

